diff --git a/src/lib/functions/netlify-function.ts b/src/lib/functions/netlify-function.ts
index baf87fb3a13..b7880d08b03 100644
--- a/src/lib/functions/netlify-function.ts
+++ b/src/lib/functions/netlify-function.ts
@@ -64,9 +64,23 @@ export default class NetlifyFunction<BuildResult extends BaseBuildResult> {
   // main file.
   public readonly srcPath: string
 
-  // Determines whether this is a background function based on the function
-  // name.
-  public readonly isBackground: boolean
+  // Determines whether this is a background function. Checks (in order):
+  //  1. ZISI build data — `invocationMode === 'background'` captures the
+  //     filename suffix AND the in-source `config.background: true`.
+  //  2. The TOML config — `[functions.<name>] background = true`.
+  //  3. The filename suffix as a last-resort fallback (used pre-build and for
+  //     non-ZISI runtimes like Go).
+  get isBackground(): boolean {
+    if (this.buildData?.invocationMode === 'background') {
+      return true
+    }
+
+    // @ts-expect-error TODO; Update the type and cut a new version of `@netlify/config`.
+    if (this.config.functions?.[this.name]?.background === true) {
+      return true
+    }
+    return this.name.endsWith(BACKGROUND)
+  }
 
   private buildQueue?: Promise<BuildResult> | undefined
   public buildData?: MappedOmit<BuildResult, 'includedFiles' | 'schedule' | 'srcFiles'> | undefined
@@ -123,8 +137,6 @@ export default class NetlifyFunction<BuildResult extends BaseBuildResult> {
     this.settings = settings
     this.srcPath = srcPath
 
-    this.isBackground = name.endsWith(BACKGROUND)
-
     const functionConfig = config.functions?.[name]
     // @ts-expect-error -- XXX(serhalp): fixed in stack PR (bumps to https://github.com/netlify/build/pull/6165)
     this.schedule = functionConfig && functionConfig.schedule
diff --git a/src/lib/functions/runtimes/index.ts b/src/lib/functions/runtimes/index.ts
index cd8c7bdfa0d..eaa9dd4f19f 100644
--- a/src/lib/functions/runtimes/index.ts
+++ b/src/lib/functions/runtimes/index.ts
@@ -21,6 +21,7 @@ export type BaseBuildResult = {
   // TODO(serhalp): This module and type shouldn't know about these zisi types. Refactor to allow the JS runtime's zisi
   // builder to define this on its extended base build result type.
   excludedRoutes?: Route[] | undefined
+  invocationMode?: string | undefined
   routes?: ExtendedRoute[] | undefined
   runtimeAPIVersion?: number | undefined
 }
diff --git a/src/lib/functions/runtimes/js/builders/zisi.ts b/src/lib/functions/runtimes/js/builders/zisi.ts
index 606cd906225..83d471f37db 100644
--- a/src/lib/functions/runtimes/js/builders/zisi.ts
+++ b/src/lib/functions/runtimes/js/builders/zisi.ts
@@ -23,6 +23,7 @@ const require = createRequire(import.meta.url)
 export type ZisiBuildResult = BaseBuildResult & {
   buildPath: string
   includedFiles: FunctionResult['includedFiles']
+  invocationMode: FunctionResult['invocationMode']
   outputModuleFormat: FunctionResult['outputModuleFormat']
   mainFile: FunctionResult['mainFile']
   runtimeAPIVersion: FunctionResult['runtimeAPIVersion']
@@ -66,6 +67,7 @@ const buildFunction = async ({
     excludedRoutes,
     includedFiles,
     inputs,
+    invocationMode,
     mainFile,
     outputModuleFormat,
     path: functionPath,
@@ -103,6 +105,7 @@ const buildFunction = async ({
     buildPath,
     excludedRoutes,
     includedFiles,
+    invocationMode,
     outputModuleFormat,
     mainFile,
     routes,
diff --git a/src/utils/deploy/hash-fns.ts b/src/utils/deploy/hash-fns.ts
index d025710d9d2..c9edc6379a3 100644
--- a/src/utils/deploy/hash-fns.ts
+++ b/src/utils/deploy/hash-fns.ts
@@ -187,7 +187,15 @@ const hashFns = async (
   const fnConfig = functionZips
     .filter((func) =>
       Boolean(
-        func.displayName || func.generator || func.routes || func.buildData || func.priority || func.trafficRules,
+        func.displayName ||
+          func.generator ||
+          func.routes ||
+          func.buildData ||
+          func.priority ||
+          func.trafficRules ||
+          func.region ||
+          func.memory ||
+          func.vcpu,
       ),
     )
     .reduce(
@@ -197,10 +205,13 @@ const hashFns = async (
           display_name: curr.displayName,
           excluded_routes: curr.excludedRoutes,
           generator: curr.generator,
+          memory: curr.memory,
+          region: curr.region,
           routes: curr.routes,
           build_data: curr.buildData,
           priority: curr.priority,
           traffic_rules: trafficRulesConfig(curr.trafficRules),
+          vcpu: curr.vcpu,
         },
       }),
       {},